On the theory of thermal diffusion in dilute polymer solutions

Abstract

Abstract The thermal diffusion coefficient in highly diluted polymer solutions is calculated. The pearl necklace model is used for description of flexible macromolecule dynamics. It is assumed that the usual diffusion equation holds under non‐uniform temperature conditions, but the coefficients of equation are variables. Free‐draining flexible macromolecules are considered. The thermal diffusion coefficient is found to be proportional to the bead diffusion constant and therefore is controlled by the kinetic flexibility of chain. In accordance with experiment the thermal diffusion coefficient does not depend on molecular weight and concentration. With eq. (9) it is possible to calculate from experimental data the bead diffusion constant and therefore to obtain the kinetic rigidity of the polymer.